The surgical outcome of pathologic N1 disease is controversial. To clarify whether pathologic N1 disease is a uniformly intermediate group or a mixed group of potentially early stage disease and advanced stage disease, we reviewed our previous cases with pathologic N1 disease. We retrospectively investigated 78 patients with pathologic N1 disease who had undergone a complete resection with mediastinal lymph node dissection during the period from April 1972 to December 1990. The cumulative postoperative survival at 5 years was 49.2%. No significant difference in the survival was found according to the following variables: sex, primary site, pathologic T factor, histologic type, type of resection, performance of adjuvant therapy. The lobar lymph nodes (Nos. 12 and 13) were only involved in 30 patients (38.5%), whereas the hilar nodes (Nos. 10 and 11) were involved in 48 patients (61.5%). The survival associated with lobar N1 disease was significantly better than that of hilar N1 disease (64.5% versus 39.7% at 5 years; p = 0.014). In lobar N1 disease, the brain was the most frequent site of distant metastasis, whereas the lungs were the most frequent site in hilar N1 disease. It was suggested that pathologic N1 disease is a mixed group of potentially early stage disease and advanced stage disease with regard to the postoperative prognosis.